Tunis: Islamist militants who have since joined Daesh claimed twin murders of secular politicians that plunged Tunisia into crisis in 2013, in a video posted online Thursday.

“Yes, tyrants, we’re the ones who killed Shukri Belaid and Mohammad Brahmi,” Abu Mouqatel, a militant wanted by the authorities for their murders, said in the video in which he appeared with several others.

It was not clear where the video was filmed but Abu Mouqatel claimed they were in an area under the control of Daesh, which has seized swathes of Syria and Iraq.

“We are going to come back and kill several of you. You will not have a quiet life until Tunisia implements Islamic law,” added the militant, whose real name is Abu Bakr Al Hakim.

Belaid was killed on February 6 last year, while Brahmi was murdered on July 25, in twin attacks blamed by the authorities on the militant Ansar Al Sharia group that had not previously been claimed.

The killing of Belaid triggered deadly protests and a political crisis that brought down Islamist prime minister Hamadi Jebali.

The murder of Brahmi intensified the crisis and threatened to derail Tunisia’s post-Arab Spring transition until a compromise government was formed in January this year.

The authorities estimate as many as 3,000 Tunisians have gone to Iraq and Syria to fight with militant groups including Daesh, and have expressed concern some will return to carry out attacks at home.